Grated drain basket with seal collar

ABSTRACT

The present invention is a basket that is sealingly insertable in a grated drain. The basket is formed from inexpensive but surprisingly tough and effective polymer grating to which is bonded polymer sheet at the upper basket edges. The polymer sheet is wide enough so that it the grate of the grated drain can be picked up and put back into its concrete inset, capturing the polymer sheet edges under its heavy weight. The captured polymer sheet forms a peripheral seal between the pavement surface and the drain so that substantially all the water must pass through the basket.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to grated water drains with inserts for capturing particulates and water contaminants.

[0002] The standard grated drain has a concrete support formed so that the top surface of the heavy duty grate lies flush with the top of the pavement. The pavement level is usually one where cars and trucks or other heavy vehicles pass over the grate. Typical locations for grated drains are in parking lots and in factories or manufacturing facilities where water gathers in sufficient quantity to require underground drainage. The grated drains often flow to environmentally sensitive bodies of water or to treatment facilities unable to process contaminants that are present in the water.

[0003] One way to try to capture a limited amount of particulates and liquid borne contaminants is described in U.S. Pat. No. 5,720,574. In that patent is described a structure for use with grated drains where an outside wall portion, a perforated bottom portion, and an inside wall portion form a trough for retention of a replaceable filter media. The trough is installed on the inside surface of a drainage structure so that drainage water that would normally flow directly through the drainage structure is caused instead to flow through the filter media, thereby removing undesirable materials that may be carried in the water, while permitting the water itself to pass through essentially unimpeded to the ultimate drainage location. Unfortunately, particulate matter that passes through the wide spaced grate effectively eliminates the passage of water through the filter media, causing the contaminated water to overflow the trough without passing through it. This device is necessarily high maintenance and is initially very costly. The metal materials must be rugged and of high alloy steel to prevent corrosion with sufficient strength to withstand maximum water and particulate flows typical of such grated drains.

[0004] U.S. Pat. No. 5,720,574 intends to provide a device and method for grated drains such as drainage inlets for sidewalks, roads and parking lots that are drainage paths for the removal of rainwater, irrigation water, or the like that would otherwise accumulate on the ground surface. However, the water thus drained from the surface by these grated drains is often undesirable and even toxic, having collected oil, fuel, antifreeze and the like. The device of U.S. Pat. No. 5,720,574 cannot prevent substantial bypass of major portions of water intended for passage through the filter media after only a relatively small amount of particulates normally present flow into the filter media.

[0005] Other references shown a variety of designs for drain inserts. U.S. Pat. No. 6,270,662 is an insert for use in a grated drain with perforated bottom surface extending across the lower periphery of the insert. A filter, resting on the perforated bottom surface, has a peripheral edge enclosing a central portion. A flange extends inwardly from the top edge of the outer wall past the peripheral edge of the filter. The flange directs drainage water past the periphery of the filter and to its more central portion, whereupon impurities within the drainage water are extracted and filtered water exits through the perforated bottom surface into the drain basin. U.S. Pat. No. 6,149,803 describes a grated drain filter with a frame of radially extending arms. The filter includes an edge piece fixed to the end of each of the arms and be engageable with a lip in a drain. Furthermore, the filter includes a filter bag, supported from the edge pieces, and wherein the filter bag has an open top for receiving water entering the drain, so that the water is filtered as it passes through the filter bag. U.S. Pat. No. 6,106,707 describes an insert for a grated drain where a hopper contains a multitude of irregular, macroscopic fragments of a hydrophobic, compliant, oil-absorbent, copolymer material having high surface area. The fragments absorb and retain permanently a high quantity of oil and other chemicals passing through the hopper, while permitting a high water flow-through rate. The fragments are held in place by a removable bottom plate, which allows replacement of the filtering fragments, and an internal basket. Trash and debris are collected in the internal basket. The hopper is configured to be suspended in a storm drain adjacent to a curb inlet on a bracket and can be installed or serviced through a conventional manhole entry. The hopper has a side cutout that permit iateral overflow from one of the modular units to an adjacent one.

SUMMARY OF THE INVENTION

[0006] The present invention is a basket that is sealingly insertable in a grated drain. The basket is formed from inexpensive but surprisingly tough and effective polymer grating to which is bonded polymer sheet at the upper basket edges. The polymer sheet is wide enough so that it the grate of the grated drain can be picked up and put back into its concrete inset, capturing the polymer sheet edges under its heavy weight. The captured polymer sheet forms a peripheral seal between the pavement surface and the drain so that substantially all the water must pass through the basket.

[0007] The polymer grating of the basket is preferably initially fabricated in an inexpensive sheet and formed into two pieces that are joined to form the basket. The formed basket can then support filter media from its upper concave or lower convex surface. The polymer sheet that extends from the periphery of the basket edges is preferably welded or heat sealed to the basket edges in an inexpensive fabrication step. The entire price of the invention basket and sealing polymer sheet is a fraction of the device of U.S. Pat. No. 5,720,574.

[0008] Filter media appropriate for the objects of the invention may comprise not only the traditional hydrocarbon capturing materials such as carbon in particles or arranged on a support, zeolites or ceramic absorbents, or diatomaceous earths, but also materials such as layered or packed fiberglass insulation or natural fiber (wood and cloth) and other such high surface area materials that will adhere 7 or more carbon hydrocarbons and other typical water contaminants from parking lot, street, industrial or agricultural runoff.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIGS. 1, 2 and 3 are respectively bottom endward perspective, bottom corner perspective and closer bottom corner perspective views of a half piece of a preferred invention basket.

[0010]FIG. 4 is a close-up view of a polymer mesh preferred for construction of the invention basket.

[0011]FIGS. 5 and 6 are respectively top perspective and bottom corner perspective views of a half piece of the invention basket with a polymer sheet bonded to a top edge.

[0012]FIG. 7 is a top view of two half pieces of the invention basked attached at an overlap zone with one half piece being substantially the same as the half piece of FIGS. 5 and 6.

[0013]FIG. 8 is a preferred outline of a flat sheet of polymer grating as in FIG. 7 showing fold and cutout lines to form an invention one half piece of the invention basket.

[0014]FIG. 9 is substantially the piece of FIG. 8 with side and end parts folded into final construction orientation except without extensions to form pockets.

[0015]FIG. 10 is an exemplary grated drain.

[0016]FIG. 12 shows the invention basket supported in the drain of FIG. 10 on spaced apart rods and where the polymer sheet is draped upon the support ledge of the grate.

[0017]FIG. 13 shows the basket and drain of FIG. 12 with the grate capturing the polymer sheet on the surface of the support ledge.

[0018]FIG. 14 shows a side cross section of the invention basket indicating potential locations of filter media.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The invention is now discussed with reference to the figures.

[0020] FIGS. 1-3 show an invention half piece 100 of the assembled invention basket. Half piece 100 comprises an end 101, sides 102, and bottom 104 of a generally one half box structure. An important aspect of the invention is to provide a drain box insert that can be formed from polymer mesh, the polymer preferably formed from thermoplastic polymers so that fabrication welds and connections can easily be made with the appropriate plastic welding or heat sealing techniques to provide exception resistance to tear and loading. A preferred polymer for the polymer mesh is inexpensive and chemically resistant polyethylene. Using a sheet of foldable thermoplastic polymer allows folds to be made along lines 105, 107 and 108 with an optional overfold section 109 resulting from material folded up along line 108 after being cut at line 103.

[0021]FIG. 4 shows a form of preferred polymer mesh. It has been found after much experimentation that several variables affect the choice of mesh opening size and mesh thickness and strut width. For devices that will receive waste liquids and potentially be too contaminated or difficult to clean to keep in consideration of cost and hazard to maintenance personnel, it is critical that low cost be achieved with full filtration ability. The prior art devices have failed to achieve anything like a low cost device for adequate filtration as in the present invention.

[0022] A preferred polymer mesh of the invention is about ¼ inch thickness polyethylene mesh with a diagonal opening width of ¼ inches. The opening size can be varied so that the hydraulic area of the mesh opening is about one half to twice that of ¼ inch thickness polymer mesh with a diagonal opening width of ¼ inches. If the opening is too small, the basket size must increase to an unmanageable size to accommodate typical flows. If the opening is too large, structural strength of an economical mesh is compromised and too many particulates will pass through the mesh opening with water flow. The preferred polymer mesh will be lightweight for ease in maintenance, insertion and removal and accomplish the objects of the invention. One object of the invention is to use polymer mesh manufactured at low cost in sheets to form the invention boxes. Another object of the invention is to form half pieces in such a manner that they can be welded, bonded or secured together after initial manufacture so that they can make a box with variable length. It is another object of the invention to form a polymer box with a sealing polymer sheet at a top edge to be secured between the grate and its support ledge.

[0023]FIGS. 5 and 6 show the half piece of FIGS. 1-3 with a polymer sheet 300 bonded, welded or sealingly secured to a top edge 1 10 of half piece 100. A polymer sheet according to the invention is not intended to support the weight of the invention box. Its thickness need only be more than about 0.5 mils or less to form an effective and low cost seal between the box edge 110 and the grate support ledge so that substantially all pavement level water and liquid is forced into the basket for filtration. Support for the inserted invention basket is by widely space support rods, or their equivalent, mounted in the walls of the drain far enough below the level of the grate support ledge so that the height of the basket and filter media is accommodated. Polymer sheet 300 is flexible and preferably thin, although it may be quite wide to accommodate support of the invention basket far beneath the level of the grate ledge. It is preferred for longer life to form polymer sheet 300 (preferably also substantially the same polymer as the polymer mesh 200 for ease in welding or heat sealing) with a thickness of greater than about 1-2 mils.

[0024] One form of the invention basket is shown in FIG. 7. Two half pieces 100 are joined at overlap 113. Before the half pieces are joined at overlap 113, they may be further moved apart to together, sliding over one another with respect to bottom 101 and sides 102 along path 114. This sliding motion makes the invention box longer or shorter when bonded at overlap 113. The invention method of producing an insertable drain box comprises making two half pieces of the same size from a polymer mesh so that they can form a box of variable length, a valuable improvement where a user's several drains are of different lengths. The user may then avoid costly inventory build up of some boxes that are too long while running short of those of lesser length.

[0025] A form of the outline of polymer mesh that will form the half pieces of FIGS. 1-3 is shown in FIGS. 8 and 9. All internal lines inside the outline are fold lines except for cut lines 103. A fold over zone 109 is shown in broken lines in FIG. 8. Optional extensions 112 are formed in the outline of FIG. 8 only. Extensions 112 can be folded inward or outward as shown in the edge lengthwise cross section of FIG. 10 so that mesh 200 that extends upward from edge zone 110 is folded at line 115 and brought over to form a pocket about a rigid support 117, where the mesh is bonded at location 117 to on itself. The pocket formed from the folding and bonding operation for the extensions 112 shown in FIG. 8 permits insertion of rigid supports, such as steel rods, after fabrication of the half piece. In a preferred embodiment, four pockets are formed along lines of extensions 112 for the two ends 102. After fabrication of the half piece to the form shown in FIGS. 1-3, the legs of a substantially square U-shaped steel rod are inserted into open ends adjacent to bottom 101 and the legs of another substantially square U-shaped steel rod are inserted into open ends adjacent to end 104. The rods are inserted until the bottom of the U-shaped rod can be captured in the remaining extensions from bottom 101 and end 104, as the case may be. These rods provide additional support for the invention basket.

[0026]FIG. 11 shows a prior art grated drain with a drain structure 118, support ledge 120 for the grate 122, a pavement level 119 for the top of the drain structure where the drain passage 121 is defined by the four walls of the drain structure 118.

[0027]FIG. 12 is a side cutaway view of FIG. 11 with the invention box and sealing sheet resting on spaced apart rods 123. Rods 123 are about ¼ to ½ inches spaced apart about 2-3 inches or more to support the weight of the invention box when it is full of water, filter material and/or rubbish or mud. Flexible sheet 300 is shown bonded at section 110 to the polymer mesh and draped over support ledge 120 up toward the top opening of structure 118. Grate 122 is shown in FIG. 12 so that it can be dropped in direction 124 to rest on support ledge 120, capturing an entire periphery of flexible sheet 300 between the grate 122 and support ledge 120.

[0028]FIG. 13 shows substantially the same structures as in FIG. 12, although optional continuous gasket material 127 is placed all around on support ledge 120 before lowering grate 122 into place to form compressed seal interface 128 all around support ledge 120. With the heavy grate 122 in place as in FIG. 13, flexible sheet material prevents bypassing of water around the invention basket and filter media. Paths 125 show that water cannot flow under flexible sheet 300, but must pass through polymer mesh of the invention basket in order to reach the drain passage 121.

[0029]FIG. 14 shows side wall zones 132 for sides of the invention basket and a single bottom zone 134 for the bottom of the invention basket. Filter media is preferably secured and/or bonded over all of lower surface 133 and/or upper surface 129 of bottom 101 so that at least some portion of water draining into the invention basket is filtered through such media. To increase the amount of liquid filtered, filter media is preferably secured and/or bonded over at least a lowest portion of outer surface 131 and/or inner surface 130 of sides 102 and ends 104 peripherally so that at more of water draining into the invention basket is filtered through such media. In another embodiment, all of the inside and/or outside surfaces of the invention basket are sealingly secured and/or bonded over those surfaces so that all liquid entering the invention basket must pass through the filter media. It is well disclosed in the prior art that filter media of predictable porosities may be chosen to remove design levels of impurities for design levels of liquid flow through those filter media. The invention basket can be adapted so that widely spaced support grating or additional polymer mesh can sealingly hold the filter media in place.

[0030] An alternate embodiment of the present invention is shown in FIGS. 15 and 16. Grated drains are sometimes installed in combination with curb drains, which combination changes important requirements for drain baskets. FIG. 16 is a side cutaway view of such a combination with the invention basket device installed, also shown in a side cutaway view similar to that of FIG. 12. In FIG. 16, a grate 122 applied in direction 124 to inset ledge 120 substantially below street level 121, where that grated drain may be installed immediately in front of a curb 141 with drain opening 142. Flow of liquids is generally from street level 121 and accumulated curb flow (not shown) into the drain opening 142 and through grate 122 when set in place.

[0031]FIG. 15 shows a preferred embodiment of the alternate embodiment of the invention where a half piece 100 as previously described is joined at living hinge or fold line 139 to hinge piece 135. It will be appreciated from inspection of FIGS. 15 and 16 that hinge piece 135 may securely and sealingly rotate about line 139. It is intended that such rotation allow the top edge 140 of front section 137 to come to rest against a rear most wall of the curb drain, as shown in FIG. 16, when the half piece 100 is place in effective position under the grate 122. The particular construction of hinge piece 135 allows the basket to adapt to a substantial range of depths 144 for grated drain and curb drain combinations. One invention combination of half piece 100 and hinge piece 135 can sealingly fit may depths 144 by allowing edge 140 of front section 137 to come to rest against the back wall. Hinge piece 135 further comprises side sealing sections 136 with top edges 138, which sections 136 are formed to effectively span the distance from the side edges of front section 137 to past the front free edges of sections 102 of half piece 100 so that liquid falling into the basket must pass through the desired polymer mesh (of which piece 135 is formed) without bypassing desired filtration materials of the invention basket. Connection between sections 102 and sections 136 are made with polymer welding, stapling or other means sufficient to result in full filtration of liquid entering the basket.

[0032] Another improvement found in the embodiment of FIGS. 15 and 16 is the sealing attachment of flexible sheet material 300 about the top periphery of the basket, i.e., along the top edges of sections 102 and 104 and edges 138 and 140. As in the previous embodiments, sheet material 300 can be captured in inset 120, although that capture is only on three sides for the drain structure of FIG. 16, substantially only for the flexible sheet material above section 104 and most of sections 102. The rest of the “un-captured” sheet material 300 may still provide effective seal to the inside walls of the curb drain by adhesive or stapling attachment of the “un-captured” sheet material 300 to a location on those inside walls above the level of the top edges of the basket. Thus, water flowing in direction 143 and splashing toward the side or rear inside walls of the curb drain will flow into the filtration surfaces of the invention basket.

[0033] The above design options will sometimes present the skilled designer with considerable and wide ranges from which to choose appropriate apparatus and method modifications for the above examples. However, the objects of the present invention will still be obtained by that skilled designer applying such design options in an appropriate manner. 

I claim:
 1. An easily insertable and removable drain box for grated drains with a grate that is supported from a support ledge comprising: (a) the grated drain having a drain passage below the support ledge with support means lodged in walls of the drain passage where open top box substantially all of polymer mesh with a top opening about the size of a lateral cross section of the drain passage of the grated drain is supported on the support means; (b) a flexible waterproof sheet sealingly attached to a top edge of the open top box and draped upward over at least substantially the entire periphery of the support ledge; and (c) the grate supported from the support ledge so that its weight sealingly captures a periphery of the flexible waterproof sheet.
 2. The drain box of claim 1 wherein the drain box is formed from two half pieces.
 3. The drain box of claim 2 wherein at least one of the half pieces is formed from a flat sheet of polymer mesh.
 4. The drain box of claim 1 wherein the drain box comprises filter media covering a bottom section so that at least part of water flowing from the pavement level is filtered therethrough.
 5. The drain box of claim 4 wherein the drain box comprises filter media on a lowermost periphery of walls of the drain box and sealingly continuous with filter media on the bottom section.
 6. The drain box of claim 1 wherein polymer mesh defines openings spaced from about 0.1 to about 0.3 inches apart and have hydraulic cross sections of from about 0.1 square inches to about 0.7 square inches.
 7. The drain box of claim 6 wherein the polymer mesh is from about 0.2 inches to about 0.5 inches thick.
 8. The drain box of claim 1 wherein the drain box is formed from two half pieces.
 9. The drain box of claim 3 wherein the polymer mesh is foldable.
 10. The drain box of claim 9 wherein the flat piece of polymer mesh defines two cut lines so that side parts are folded forming overlap zones in the assembled box.
 11. The drain box of claim 3 wherein two half pieces are slidable over each other's mirror image bottom and side sections thereby shortening or lengthening the box.
 12. The drain box of claim 11 wherein an overlap of the two half pieces at the bottom and side sections is secured together.
 13. The drain box of claim 1 wherein pocket means formed at top edges of the drain box are adapted to encase rigid support rods.
 14. The drain box of claim 13 wherein two pocket means opposite each other secure legs of a U-shaped rigid support rod.
 15. The drain box of claim 14 wherein pocket means between the two opposite pocket means secures a bottom section of the U-shaped rigid support rod. 